Responses of 122 children were obtained on two measures of central auditory processing to establish normative data. Children aged 6.5 through 12.5 years were tested for humming and tapping responses to the Pitch Pattern Sequence Test (PPST) and the two- and four-digit Dichotic Digit Tests (DDT). Children between ages 6.5 and 9.5 years showed progressively better scores on the tapping response of the PPST and on the four-digit DDT. Children above 9.5 years of age demonstrated adult-like responses on both tests. No differences were demonstrated in performance of children aged 6.5 through 12.5 years on the two-digit DDT or on the humming response of the PPST.

published_or_final_version / abstract / Speech and Hearing Sciences / Master / Master of Science in Audiology

Dichotic tests evaluate binaural integration through simultaneous presentation of different stimuli to each ear of a listener who has normal hearing sensitivity in both ears. Dichotic listening deficits may lead to problems with language, communication, reading, or academic performance. If accurately identified, dichotic deficits may be treatable with listening training or managed with accommodation. However, it is not clear which of several commercially-available dichotic test recordings are best for audiologists to use when assessing binaural integration in children. Literature review revealed limited evidence of reliability, accuracy, usefulness, or value for dichotic tests applied to children. Of 11 dichotic tests identified, five reported some evidence of test-retest reliability. Correlation between results on repeated administration was moderate to good (r=0.59 to 0.92). Evidence of accuracy was identified for 5 tests but was not generalizable due to significant limitations in study design. No evidence was found to either support or dispute claims of usefulness or value. Since reliability is a necessary prerequisite for good test performance, we sought to directly compare test-retest reliability for three dichotic measures: SCAN-3 Competing Words (CW), Musiek's Double Dichotic Digits (DD-M), and Bergen Dichotic Listening Test with Consonant-Vowel Syllables (CV-B). Sixty English-speaking children, 7-14 years old with normal hearing, had a single study-visit during which each test was administered twice. Changes on retest were compared to binomial model predictions, summarized by within-subject standard deviation (Sw), and compared among tests. Correlates of variance were explored. All 3 tests had reliability within bounds predicted by binomial model. Forty-item scores were more reliable (Sw=5%) than those based on 20-30 items (Sw=6-8%). No associations between participant characteristics and reliability were found. CW and DD-M were evaluated for evidence of agreement and decision consistency. Although participants were rank ordered similarly by right ear (ρ = 0.58), left ear (ρ = 0.51) and total (ρ = 0.73) scores, the tests did not agree on ranking by inter-aural asymmetry (ρ =0.18). CW and DD-M did not agree on direction of ear advantage (κ = 0.01, p = 0.93) and had poor agreement on which children displayed dichotic deficits (κ = 0.22, p < 0.01). DD identified significantly more participants with deficits (n=18) than CW (n=3) (p < 0.001). Although dichotic procedures show moderate reliability, their precision is limited. Assessment of their accuracy is limited by the absence of a widely-accepted gold standard reference test, but two commonly used tests failed to agree on which children had deficits. The data do not yet support routine clinical use of dichotic tests of binaural integration with children. Additional research is needed to determine if there are any conditions under which dichotic procedures demonstrate usefulness or value.

Diss. Linköping : Universitetet, 2005.

Two separate methods are presented to aid in the creation and evaluation of acoustic simulations. The first is a hybrid method that allows separate low and high-frequency acoustic responses to be combined into a single broadband response suitable for auralization. The process consists of four steps: 1) creating separate low-frequency and high-frequency responses of the system of interest, 2) interpolating between the two responses to get a single broadband magnitude response, 3) adding amplitude modulation to the high-frequency portion of the response, and 4) calculating approximate phase information. An experimental setup is used to validate the hybrid method. Listening tests are conducted to assess the realism of simulated auralizations compared to measurements. The listening tests confirm that the method is able to produce realistic auralizations, subject to a few limitations. The second method presented is a machine learning approach for predicting human perceptions of audio fidelity and sound quality. Several algorithms are compared and various audio features considered in developing the machine learning models. The developed models accurately predict human perceptions of audio fidelity and sound quality in three distinct applications: assessing the fidelity of compressed audio, evaluating the fidelity of simulated audio, and comparing the sound quality of loudspeakers. The high accuracies achieved confirm that machine learning models could potentially supplant listening tests, significantly decreasing the time required to assess audio quality or fidelity.

The new compact disc from the Department of Veterans Affairs, Tonal and Speech Materials for Auditory Perceptual Assessment, Disc 2.0 (1998), contains two lists of randomly interleaved 1-, 2-, and 3-pair dichotic digits. Two experiments are reported, in which the effects of low-pass filtering and inter-digit interval on dichotic digit recognition were investigated in adult listeners with normal hearing and with mild-to-moderate cochlear hearing loss. Results demonstrated that in the filtered condition, as the low-pass cutoff was increased, there was an increase in recognition performance for 1-, 2-, and 3-pair dichotic digits. When compared to normative data for the materials, findings indicate that the interleaved 1-, 2-, and 3-pair dichotic digit materials were essentially resistant to the effects of hearing loss. There was no significant change in recognition performance as a function of inter-digit interval. The studied 625-ms range of inter-digit intervals studied produced consistent recognition performance with both groups of listeners.

Dichotic listening was evaluated in free-recall and directed-recall (pre-cued, post-cued) response conditions using interleaved one-, two-, and three-pair dichotic digit materials. In the free-recall condition, the subjects recalled in any order the digits presented. In the directed-recall condition, a response task was examined where subjects recalled all digits presented to the cued ear (pre- or post-cued) followed by the digits presented to the opposite (non-cued) ear. Thirty 20- to 29-year-old adults with normal hearing and 30 60- to 79-year-old adults with mild-to-moderate sensorineural hearing loss were evaluated. In all conditions, performance by the younger listeners was better than performance by the elderly listeners. As the difficulty of the dichotic digit task increased, recognition performance decreased. The recognition performance of elderly listeners was more affected by increases in the difficulty of the stimulus materials as compared to the younger listeners. In the free-recall condition, there was a right-ear advantage for both age groups. When instructional bias was imposed, the results favored the ear of instructed bias. The differences in recognition performance between young and elderly listeners likely reflect differences in the difficulty of the dichotic digit test conditions and variations in the demand on auditory memory.

Sound quality analysis is a tool designed to help determine customer preferences, which can be used to help the designer improve product quality. Many industries desire to know how the consuming public perceives their product, as this affects the product life and success. This research investigates which of the six sewing machines provided by Viking Sewing Machine Group (VSM group) consumers find most acoustically appealing. The sound quality analysis methods used include both jury based listening tests and quantitative sound quality metrics from empirical equations. The results from both methods are completely independent and are shown to have a very strong correlation. The procedures and results of both methods, jury listening tests and mathematical metrics, are presented. Near field sound intensity scans identified acoustic hot spots and give direction for possible design modifications to improve the acoustic signature of the two top tier machines, the Designer 1 and Creative 2144 (Husqvarna Viking and Pfaff respectively). This research determined that the entry level Pfaff Select 1530 has the most acoustically appealing sound of the six machines evaluated. In addition, it was also determined that a reduction in the higher frequency sounds produced by the machines is preferred over a reduction in the lower frequency sounds. Further investigations, including an evaluation of machine isolation and startup sounds, were also performed. The machine isolation results are highly dependant on the individual machine being evaluated and would require independent evaluation. In the machine startup sound assessment, it was discovered that again the Pfaff Select 1530 has the preferred sound. Near field acoustic intensity scans provide additional information on locations of strong acoustic radiation. The near field scans provided valuable design information. The acoustic "hot" spots were discovered to exist in the lower portions of the machines near the main stepper motor in the Designer 1, and radiating from the bottom plate of the machine in the Pfaff Creative 2144. This analysis has led to various design modifications that could be implemented to improve the sound quality of the machines, specifically the Designer 1 and the Creative 2144.

The Dichotic Emotional Words Tape developed by Bryden and MacCrae (1989) was used to assess cerebral asymmetry for propositional and nonpropositional speech as a function of verbal fluency. Forty-five right-handed subjects with normal auditory acuity for pure tones were assigned to a verbal fluency classification based on scores on the FAS test (Borkowski, Benton, & Spreen, 1967). After being assigned to a fluency category, subjects were instructed to listen for a word (bower, dower, power, or tower) or affective tone (happy, sad, angry, or neutral). The most important findings of this study were the main effects of fluency (higher, middle, and lower), stimulus type (word and affect), and focus or intention (focus left and focus right). Subjects higher in fluency exhibited significantly greater REA and LEA scores than subjects lower in fluency. For stimuli presented to the right ear, scores for words were significantly greater than scores for affect. However, for stimuli presented to the left ear, scores for affect were significantly greater than scores for words. Focus left instructions led to increases in LEA scores, while focus right instructions led to increases in REA scores. Directions for future research are discussed. / Master of Science

Realizou-se um inventário quantitativo e qualitativo das características demográficas e dos erros cometidos nos itens dicóticos do Teste de Dissílabos Dicóticos Alternados, também conhecido como SSW em português, com as informações de 722 sujeitos que completaram este teste nos anos de 1994 a 2001. Os resultados revelaram que a amostra estudada foi composta em sua maioria de sujeitos do sexo masculino, cursando as séries iniciais do ensino fundamental, relatando dificuldades de fala, escria e leitura e neurologicamente normais, com desordem de processamento auditivo do tipo decodificação, de grau leve/moderado. Uma tendência de erro em alguns itens dicóticos do teste foi observada. / A total of 722 subjects provided the information for the quantitative and qualitative inventory of demographic features and the errors observed in the dichotic items of the Portuguese version of the SSW Test. Results revealed that, collectively, these subjects were mostly males, in elementary school, referring speech, reading and writing difficulties, and not presenting neurological disorders. They also presented a decoding-type auditory processing disorder of mild/moderate severity. Error and performance profiles were characterized by multivariate statistics.